1. Field of the Invention
The present invention relates to a storage system and a method of controlling the same.
2. Description of the Related Art
Disaster recovery is important in an information-processing system. As a technique for recovery from a disaster, the standard technique is known to store and manage a copy of the data on a storage device at a primary site by a storage device located at a remote site (hereinafter, this technique is referred to as ‘remote copy’). According to this technique, when the primary site is damaged, processes performed at the primary site are continuously performed at the remote site by using data in the storage device located at the remote site.
In the above-described method, in order to continue to perform the process that was being performed at the primary site at the remote site when the primary site is damaged, it is necessary to perform a remote copy from the primary site to the remote site in real time. However, the primary site and the remote site are often separated distantly from each other. Therefore, if the remote copy from the primary site to the remote site is performed in real time, it takes a considerable amount of time for data communication, and the processing performance of the primary site is decreased. In an information-processing system required for high availability (HA), the processing performance of the primary site should not be decreased, and the process should be rapidly resumed at the remote site when the primary site is damaged.